| Tiny Mercury, the innermost planet in the solar system, appears to have a partially liquid core. |
太陽系最里面的微型行星——水星好象有著半液態(tài)的核心。 |
| That new finding may help explain the planet's weak magnetic field, even as it opens more puzzling questions about how the core has maintained a semi-liquid state for billions of years. |
這個新發(fā)現(xiàn)可能有助于解釋水星的弱磁場?？墒?，幾十億年來水星核心是如何保持半液體狀態(tài)的？對于這個情況，該發(fā)現(xiàn)引出了更多的疑難問題。 |
| Because of its small size - Mercury is 40% smaller than Earth - the laws of physics suggest that its core should have cooled and solidified long ago. But an innovative radar technique that measured Mercury's rate of rotation shows distinctive signs that the planet consists of both solid and semi-liquid matter. |
水星比地球小40％。由于水星體積小，根據(jù)物理法則，其核心本應(yīng)該在很久以前就已經(jīng)冷卻并且凝固起來。然而，利用一項測量水星自轉(zhuǎn)速度的雷達(dá)創(chuàng)新技術(shù)，所測得的獨特信號顯示，水星的組成成分中既有固態(tài)物質(zhì)，也有半液態(tài)物質(zhì)。 |
| "What we've been able to do from the ground is to detect tiny changes in the spin rate of Mercury that indicates the planet has a molten core," says astronomer Jean-Luc Margot, an assistant professor at Cornell University. "The molten core tells us something very important about the planet's body temperature. A planet the size of Mercury should have cooled off by now. It should have radiated all its heat," he says. |
“我們在地面上所能夠做的就是：探測水星自轉(zhuǎn)速度的細(xì)微變化，這種細(xì)微變化說明水星擁有一個熔化的核心，”天文學(xué)家、康奈爾大學(xué)助理教授吉恩-盧克·馬戈特說。他指出：“有關(guān)水星的表面溫度問題，這個熔化的核心向我們說明了極其重要的情況。到現(xiàn)在為止，象水星大小的行星本應(yīng)該已經(jīng)散發(fā)出所有的熱量而冷卻下來。” |
| The finding, published today in the journal Science, helps to explain the weak magnetic field the Mariner 10 probe detected during fly-bys in the mid-1970s. |
該發(fā)現(xiàn)發(fā)表在今天出版的《科學(xué)》雜志上。20世紀(jì)70年代中葉，“水手”10號探測器飛臨水星的時候發(fā)現(xiàn)水星的磁場很弱，目前的發(fā)現(xiàn)有助于解釋這個情況。 |
| One way for a planet to generate a magnetic field is to have a core of liquid or semi-liquid metal, like Earth's. But the discovery also raises the question of what factors are keeping Mercury's interior hot enough to remain molten. |
能夠使行星產(chǎn)生磁場的一種情形是：跟地球一樣，擁有液態(tài)或半液態(tài)金屬核心。但是，該發(fā)現(xiàn)也提出了如下問題：哪些因素在保持著水星內(nèi)部的熱度，足以使其核心保持熔化狀態(tài)？ |
| One possibility is that heat-trapping lighter elements, such as sulfur, are doing the trick. But scientists are stumped as to how those elements could condense in a place so close to the Sun. "The people doing thermal evalution calculations are certainly scratching their heads figuring out what you need to explain a molten core in such a small planet," Margot says. |
一種可能性就是善于捕捉熱量易燃元素（如：硫磺）在作怪。但是，這些元素為何可以聚集在離太陽如此近的地方，科學(xué)家們對此感到困惑。“進(jìn)行熱量評估計算的研究人員肯定會感到迷惑不解，他們會考慮：該拿什么來解釋如此小型行星中的熔化核心呢？”馬戈特說。 |
| More answers may come when NASA's Messenger spacecraft arrives at Mercury. The probe is expected to make three fly-bys before settling into orbit for long-term studies in 2011. The first pass will come in January. Scientists were awaiting Messenger's arrival to resolve, among other questions, the mystery of the planet's core. |
美國航空航天管理局的“信使”號太空船到達(dá)水星后，也許會進(jìn)一步找到答案。預(yù)計該探測器將飛臨水星3次，然后于2011年進(jìn)入軌道，以實施長期研究任務(wù)。一月份，“信使”號太空船將首次經(jīng)過水星?？茖W(xué)家們在等待“信使”號的到達(dá)，以便解決問題，尤其是水星核心之謎的問題。 |
| But Margot and his colleagues beat them to it using pairs of radio telescopes in California, West Virginia and Puerto Rico to bounce radar signals off Mercury and measure the reflected signals on Earth. |
然而馬戈特及同事捷足先登，他們利用加利福尼亞、西弗吉尼亞和波多黎各的射電望遠(yuǎn)鏡發(fā)回水星的雷達(dá)信號，然后在地球上測量水星的反射信號。 |
| Margot likens the technique to watching the patterns of light on a wall cast by a circling disco ball. By knowing the exact distance between two set points on the wall, for example, subtle variations in the ball's spin rate can be measured. |
馬戈特把這個技術(shù)比作是：觀看迪斯科舞廳里旋轉(zhuǎn)的球形燈投射在墻壁上的燈光圖案。例如，了解到墻壁上兩個定點之間的確切距離，球形燈旋轉(zhuǎn)速度的細(xì)微變化就可以測量了。 |
| The team made more than 20 observations of Mercury between 2002 and 2006. |
在2002年到2006年之間，該研究小組對水星進(jìn)行了20 多次觀測。 |
| "The technique was not fully appreciated ... until a few years ago," Margot says. "At that point I started looking into it and saw that it had potential. We could have done years ago." |
“這項技術(shù)直到幾年前才被充分重視起來，”馬戈特說，“那時我開始研究該技術(shù)，結(jié)果發(fā)現(xiàn)它擁有潛在的利用價值。我們本來在幾年前就可以拿下這項任務(wù)的。” |
